The resultant of two equal velocities is equal to either. What is the angle between them?

Explanation

Let two vectors of magnitude a be inclined at an angle `theta` with each other. Then their resultant is
`a^(2)=a^(2)+a^(2)+2a^(2) cos theta`
`rArr a^(2)=2a^(2)(1+cos theta)`
`rArr 1+cos theta=(1)/(2) or cos theta =-(1)/(2)`
`rArrtheta=120^(@)`
So, when the angle between two vectors of equal magnitude is `120^(@)` , their resultant is equal to the magnitude of either vector .